The Sir Joseph Banks Group is an archipelago of about 20, mostly small, islands, with a collective land area of 1275 ha, lying in Spencer Gulf about 20 km off the eastern coast of the Eyre Peninsula in South Australia. It is an important seabird breeding site.
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The islands were visited and named by Matthew Flinders in February 1802 on his voyage of exploration in HMS Investigator. The group is named after Sir Joseph Banks, who was a sponsor of the Investigator voyage. Many islands in the group are named after places in Lincolnshire, England, Flinders’ home county.
The islands are low-lying, with the highest point on Spilsby of about 50 m. They consist mainly of a granite base beneath limestone and are usually capped with calcrete or sandy soil. Reevesby and Spilsby are the largest islands in the group. Eighteen of the islands are protected in the Sir Joseph Banks Group Conservation Park, while the surrounding waters are protected in a 2627 km2 marine park. Spilsby Island is privately owned and continues to be grazed by sheep, as well as holding a few holiday cottages.[1]
Most islands are vegetated with low shrubland dominated by Nitre Bush or African Boxthorn. Some support tall shrubland dominated by Coastal Boobialla or Coastal Daisybush. Areas of sandy loam may support Marsh Saltbush. The larger islands retain patches of woodland. Islands previously used for grazing sheep have introduced grasses and Burr Medick.[1]
As well as the native Death Adders, Tiger Snakes, and several species of lizard including goannas, many of the islands have introduced mammals such as feral cats, House Mice or Chinchilla rabbits. The archipelago has Australian Sea Lion breeding colonies. Greater Stick-nest Rats were reintroduced to Reevesby Island in 1990/91.[1]
The archipelago has been identified by BirdLife International as an Important Bird Area (IBA) because it supports over 1% of the world populations of White-faced Storm Petrels (with up to about 180,000 breeding pairs), Cape Barren Geese (up to about 1200 individuals), Black-faced Cormorants (from 3000 to 5000 breeding pairs), and, probably, of Pacific Gulls.[2] Other seabirds which breed in the archipelago include Little Penguins, Silver Gulls and Greater Crested Terns. Fairy Terns and Eastern Reef Egrets have been recorded.[1]
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Visits to the islands are only possible by boat, with the closest mainland access point the coastal town of Tumby Bay, 22 km to the north-west. Some islands are not open to the general public because of their environmental sensitivity.